The invention relates to a container. More particularly, the invention relates to the structure of a container for liquids.
Recent increases in bulk purchasing have created a demand for large-size liquid containers. Many liquid products are now sold to the consuming public in plastic containers that can be as large as several liters. Larger containers that hold heavy fluids, including beverages, home products, motor oil, or the like, must have a structure strong enough to withstand several different forces. Such forces include, for example, those that result from the weight of the fluid itself, rough handling during transportation, stacking during storage, and being dropped.
A container that is commonly used as a large plastic container is the polyolefin continuous extrusion blow-molded container. Polyolefin continuous extrusion blow-molded containers provide the requisite structure to resist many forces, particularly those related to top-loading.
It will be understood that to form a polyolefin continuous extrusion blow-molded plastic container, a plastic can be heated in an extruder and a parison is created by the plastic exiting the extruder through the head tooling. The parison is then captured by a mold, and blown in the mold. Specifically, to form the cavity of the container, a parison can be extruded up into the mold and as the mold comes together, a pneumatic blow pin, for example, can pierce the parison and blow the parison up against the walls of the mold. The mold typically contains flash pockets above and below the cavity in the mold to capture the excess of the parison that is forced above and below the cavity. When the parison is blown inside the mold, it is forced into the flash pockets and portions of the parison must adhere together. The excess flash can then be cut away from the container after it is ejected from the mold.
There is a need for a large container having a structure that can withstand, in particular, the top load forces that result from stacking of multiple layers of filled containers. The structures should be capable of accommodating variations in volume of the containers' contents. Furthermore, the structure should be capable of being manufactured in conventional high-speed equipment.